On Thu, May 12, 2016 at 07:04:15PM +0530, Bharata B Rao wrote: > memory_hotplug_max() uses hot_add_drconf_memory_max() to get maxmimum > addressable memory by referring to ibm,dyanamic-memory property. There > are three problems with the current approach: > > 1 hot_add_drconf_memory_max() assumes that ibm,dynamic-memory includes > all the LMBs of the guest, but that is not true for PowerKVM which > populates only DR LMBs (LMBs that can be hotplugged/removed) in that > property. > 2 hot_add_drconf_memory_max() multiplies lmb-size with lmb-count to arrive > at the max possible address. Since ibm,dynamic-memory doesn't include > RMA LMBs, the address thus obtained will be less than the actual max > address. For example, if max possible memory size is 32G, with lmb-size > of 256MB there can be 127 LMBs in ibm,dynamic-memory (1 LMB for RMA > which won't be present here). hot_add_drconf_memory_max() would then > return the max addressable memory as 127 * 256MB = 31.75GB, the max > address should have been 32G which is what ibm,lrdr-capacity shows. > 3 In PowerKVM, there can be a gap between the end of boot time RAM and > beginning of hotplug RAM area. So just multiplying lmb-count with > lmb-size will not provide the correct max possible address for PowerKVM. > > This patch fixes 1 by using ibm,lrdr-capacity property to return the max > addressable memory whenever the property is present. Then it fixes 2 & 3 > by fetching the address of the last LMB in ibm,dynamic-memory property. > > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> arch/powerpc/mm/numa.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 4a87ccb..f8b1da7 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1164,17 +1164,33 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
> static u64 hot_add_drconf_memory_max(void)
> {
> struct device_node *memory = NULL;
> + struct device_node *dn = NULL;
> unsigned int drconf_cell_cnt = 0;
> u64 lmb_size = 0;
> const __be32 *dm = NULL;
> + const __be64 *lrdr = NULL;
> + struct of_drconf_cell drmem;
> +
> + dn = of_find_node_by_path("/rtas");
> + if (dn) {
> + lrdr = of_get_property(dn, "ibm,lrdr-capacity", NULL);
> + of_node_put(dn);
> + if (lrdr)
> + return be64_to_cpup(lrdr);
> + }
>
> memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
> if (memory) {
> drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
> lmb_size = of_get_lmb_size(memory);
> +
> + /* Advance to the last cell, each cell has 6 32 bit integers */
> + dm += (drconf_cell_cnt - 1) * 6;
> + read_drconf_cell(&drmem, &dm);
> of_node_put(memory);
> + return drmem.base_addr + lmb_size;
> }
> - return lmb_size * drconf_cell_cnt;
> + return 0;
> }
>
> /*
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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